$-\dfrac{6}{2} - \dfrac{6}{3} = {?}$
Answer: $ = - {\dfrac{6 \times 3}{2 \times 3}} - {\dfrac{6 \times 2}{3 \times 2}} $ $ = - {\dfrac{18}{6}} - {\dfrac{12}{6}} $ $ = - \dfrac{{18} - {12}}{6} $ $ = -\dfrac{30}{6}$